Smart cards are well known in the industry as being credit cards having computer chips embedded therein which are connected to metallic contact pads on a major surface of the credit card. These smart cards are insertable into card readers which make electrical contact with the pads of the card through contacts mounted in the card reader housing. Some card readers are provided with end of position switches to detect that a card has been inserted and is located in a read position. The switch serves to detect the card location and actuate a read circuit in the system. Card reading will therefore not be initiated until the card is detected as being in the read position.
One example of such a card reader including an end of position switch is disclosed in U.S. Pat. No. 5,334,827 by Bleier et al. Bleier et al. show a sliding type reader in which a smart card is inserted into the reader and is slid over the contacts until they are aligned with the pads of the smart card. The contacts are spring loaded against the card while the card is slid into the read position. A normally closed end of position switch is provided to detect that the card is in the read position.
A problem exists with these sliding-type card readers as disclosed by Bleier et al. in that excess wear occurs on the reader contacts due to a long wiping path at a high normal force during the mating and unmating cycle. As a result, debris is picked up by the reader contacts as they slide along the card surface. This debris is then deposited onto the card mating pads making it difficult to achieve a reliable electrical connection. Additionally, the debris can be deposited between the switch contacts to interrupt switch closure and therefore falsely indicate that a card is inserted in the read position.
A further problem exists with these types of card readers in that they typically utilize molded housings to provide guidance and alignment of the card within the card reader. When cards repeatedly come in contact with such plastic housing guiding or alignment members, dust/debris is generated as the two surfaces wear against each other. After many mating cycles, this dust/debris settles on the reader or switch contacts and the card mating pads to have a degrading effect on the electrical performance of the reader.
It is desirable in some systems to have a normally open end of position switch as opposed to the normally closed switch discussed above. Changing configuration of the switch typically would require redesigning the entire card reader so that insertion of a card would affect a closing of the switch instead of affecting an opening of the switch. Reichardt et al. disclose such a configurable switch in U.S. Pat. Nos. 5,334,034 and 5,370,544. The end of position switch as taught by Reichardt et al. includes two switching contact elements arranged to either close or open to detect that the card has reached the read position. While this card reader eliminates the need to redesign the reader in order to achieve different switch configurations, the same problem exists in that debris caused by the sliding actions may be deposited on the reader contacts or the switch contacts to adversely affect the electrical performance of the connector.